Struct Date 

pub struct Date { /* private fields */ }

A calendar date (year, month, day) in the proleptic Gregorian calendar, with no time of day and no time zone.

The year is limited to 0..=9999, so the ISO 8601 form YYYY-MM-DD always has four year digits. Dates compare chronologically. Being a plain calendar date, it cannot express “now”: to get today’s date, convert a unix time with Date::from_unix_days (the current time is an input, never read behind your back).

Examples

use helpers4::date::Date;

let date = Date::new(2026, 9, 23)?;
assert_eq!(date.to_string(), "2026-09-23");
assert_eq!(date.add_days(10), Some(Date::new(2026, 10, 3)?));
assert_eq!("2024-02-29".parse::<Date>(), Date::new(2024, 2, 29));

Implementations

impl Date

pub fn new(year: i32, month: u8, day: u8) -> Result<Self, DateError>

Builds a date, checking that it exists.

Arguments

• year - The year, 0..=9999.
• month - The month, 1..=12.
• day - The day of the month, 1 to the length of that month.

Errors

DateError::InvalidYear, DateError::InvalidMonth or DateError::InvalidDay when the date does not exist (such as February 30th).

pub fn parse(text: &str) -> Result<Self, DateError>

Parses the ISO 8601 form YYYY-MM-DD.

Exactly four year digits, two month digits and two day digits, separated by hyphens: no spaces, signs or time of day.

Arguments

• text - The text to parse.

Errors

DateError::InvalidFormat when the text does not have that shape, or the errors of Date::new when it has the shape but names a date that does not exist.

pub fn year(self) -> i32

The year, 0..=9999.

Returns

The year.

pub fn month(self) -> u8

The month, 1..=12.

Returns

The month, 1 for January.

pub fn day(self) -> u8

The day of the month, starting at 1.

Returns

The day of the month.

pub fn is_leap_year(self) -> bool

Whether the year of this date is a leap year.

Returns

true for a date in a leap year.

pub fn weekday(self) -> Weekday

The day of the week.

Returns

The Weekday this date falls on.

pub fn ordinal(self) -> u16

The day of the year: 1 for January 1st, 365 (or 366) for December 31st.

Returns

The ordinal day, 1..=366.

pub fn unix_days(self) -> i64

The number of days since 1970-01-01 (negative before it).

Returns

The day count, the same one Date::from_unix_days reads back.

pub fn from_unix_days(days: i64) -> Option<Self>

The date days days after 1970-01-01 (before it when negative).

Arguments

• days - The day count since 1970-01-01, for instance unix_seconds / 86_400 (rounded down) for a UTC date.

Returns

The date, or None when it falls outside the years 0..=9999.

pub fn add_days(self, days: i64) -> Option<Self>

The date days days after this one (before it when negative).

Arguments

• days - How many days to move.

Returns

The new date, or None when it falls outside the years 0..=9999.

pub fn days_until(self, other: Self) -> i64

The number of days from this date to other.

Arguments

• other - The date to count to.

Returns

Positive when other is later, negative when it is earlier, 0 for the same date.

Trait Implementations

impl Clone for Date

fn clone(&self) -> Self

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for Date

impl Debug for Date

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Display for Date

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Eq for Date

impl FromStr for Date

type Err = DateError

The associated error which can be returned from parsing.

fn from_str(text: &str) -> Result<Self, Self::Err>

Parses a string s to return a value of this type.

impl Hash for Date

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl Ord for Date

fn cmp(&self, other: &Self) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

where Self: Sized,

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

where Self: Sized,

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

where Self: Sized,

Restrict a value to a certain interval.

fn clamp_to<R>(self, range: R) -> Self

where Self: Sized, R: ClampBounds<Self>,

🔬This is a nightly-only experimental API. (clamp_to)

Restrict a value to a certain range.

impl PartialEq for Date

fn eq(&self, other: &Self) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl PartialOrd for Date

fn partial_cmp(&self, other: &Self) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

fn lt(&self, other: &Rhs) -> bool

Tests less than (for self and other) and is used by the < operator.

fn le(&self, other: &Rhs) -> bool

Tests less than or equal to (for self and other) and is used by the <= operator.

fn gt(&self, other: &Rhs) -> bool

Tests greater than (for self and other) and is used by the > operator.

fn ge(&self, other: &Rhs) -> bool

Tests greater than or equal to (for self and other) and is used by the >= operator.

impl StructuralPartialEq for Date